1. Field of the Invention
The invention relates generally to a feed unit for a machine tool. More particularly, the invention relates to a cam feed unit for controlling the movement of a machine tool toward and away from a workpiece.
2. Summary of Related Art
Machine tools, such as automatic lathes or automatic plunge type grinders, are usually comprised of a headstock having a rotatable spindle to support a workpiece and a tool carrying slide which is movable toward and away from the workpiece. A feed unit is generally provided for controlling the movement of the tool slide so that the tool slide can be advanced rapidly toward and away from the workpiece both before and after the actual machining operation, while being slowly fed toward the workpiece during the machining operation.
In the past, the feed unit for such machine tools was typically comprised of a single hydraulic cylinder with a servo-type valve having adjustable feeds. Such feed units, however, often provided relatively inconsistent feed of the tool slide and inadequate operator control. In response, many more recently produced automatic machine tools include computer numerically controlled feed units which provide greatly improved consistency, accuracy and ease of control. While such systems have performed well, they are relatively complex and may be prohibitively expensive in some instances.